Certain water-soluble high molal oxyalkylated esters and method of making same



Patented Sept. 28, 1943 OXYALKYLATED ESTEBS AND OF MAKING SAME IMETHOD t Melvin De Groote, University City, and Bernhard Kelser, Webster Groves, Mo., assignora to Petrolite Corporation, Ltd. Wilmington, DeL. a corporation of Delaware no Drawing. Original application March 21,

1941, Serial No. 884,600. Divided and this application June 26, 1942, Serial No. 484,686

11 Claims. (c1. zen-404.8)

This invention relates to a new chemical product or compound, our present application being a division of our co-pending application Serial No. 384,600, filed March 21, 1941, now U. 8. Patent No.

2,295,168, dated September 8, 1942.

One object of our present invention is to provide a new material, compound or composition of matter, that is capable of use for various purposes, and particularly adapted for use as a demulsifler in the resolution of crude oil emulsions.

Another object of our inventionis to provide a practicable method for manufacturing said new material, compound or composition of matter.

The new chemical compound or composition of matter which constitutes our present invention is exemplified by the acid, or preferably, neutral ester derived by complete esteriflcation of one mole of a polyallwlene glycol of the kind hereinafter described, withtwo moles of a fractional ester derived from a hydroxylated material of the kind herein described, and a polybaslc carboxy acid having not over six carbon atoms.

If a hydroxylated material, indicated for the sake of convenience by the formula T.0H, is reacted with a polybasic carboxy acid, which, similarly, may conveniently be indicated as being of the dibasic type, by the formula HOOC.D.COOH, then the fractional ester obtained by reaction between equimolar quantities may :be indicated by the following formula:

HOOCD.COO.T

The polyethylene glycol may be characterized by materials of the kind such as heptaethylene glycol, octaethylene glycol, nonaethylene glycol,

decaethylene glycol, to and including heptadecaethylene glycol. For convenience, these poly ethylene glycols may be indicated by the follow ing formula:

OHiCzHrOhH in which 112. varies from 7 through 17.

Instead of polyethylene glycols, one may use polypropylene glycols or polybutylene glycols. Thus, for convenience, in the broadest aspect, the polyalkylene glycols employed may be indicated by the following formula:

'r.ooc.n.coon+omcimoitn+ above described, with two moles ester of the kind previously indicated. The formation of the compound may be indicated by the following reaction, although obviously, it is immaterial what particular procedure is em-.

ployed to produce the particular pound or product:

chemical com- As indicated previously," the polybasic acids employed are limited to the type having not more than six carbon atoms, for example, oxalic, malonic, succinic, glutaric, and adipic. Similarly,

one may employ acids such as fumaric, maleic,-

glutaconic, and various others, including citric, malic, tartaric,;and the like. The selection of the particular tribasic or dibaslc acid employed is usually concerned largely with convenience of manufacture of the finished ester, and also of the price of the reactants. Generally speaking, the higher the temperature employed, the easier it is to obtain large yields of the esteriiied product. Although oxalic acid is comparatively cheap, it decomposes somewhat readily at slightly above the boiling point of water. For this reason it is more desirable to use an acid which is more resistant to pyrolysis. Similarly, when a polybasic acid is available in the form of an anhydride, such anhydride is apt to produce the ester with greater ease than the acid itself. ,For this reason, maleic anhydride is particularly adaptable; and also, everything else considered, the cost is comparatively low on a per molar basis, even though somewhat higher on a per pound basis. Succinic acid or the anhydride has many of the attractive qualities of maleic anhydride; and. this is also true of adipic acid. For purposes of brevity, the bulk of the compounds hereinafter illustrated will refer to the use of maleic anhydride, although it is understood that any other suitable polybasic acid may be employed. Furthermore, for purposes of convenience, reference is made to the use of polyethylene glycols. As has been previously indicated, such glycols can be replaced by suitable polypropylene or polybutylene compounds.

As far as the range of oxyalkylated compounds employed as reactants is concerned, it is our preference to employ those having approximately 8-12 oxyalkylene groups, particularly 8-12 oxy-' ethylene groups. The preference to use the oxyethylated compounds is due largely to the fact that they are commercially available, and parof a fractional tlcularly so in two desirable forms. The most desirable form is the so-called nonaethylene glycol. which, although consisting largely of nonaethylene glycol, may contain small amounts of heptaethylene and octaethylene glycols, and possibly minor percentages of the higher homologs. Such glycols represent the upper range of distillable glycols; and they may be conveniently referred to as upper distillable ethylene glycols." There is no particularly good procedure for making a sharper separation on a commercial scale; and it is understood that mixtures of one or more of the glycols may be employed, as well as a single glycol. As pointed out, it is particularly preferred to employ nonaethylene g ycol as commercially available, although it is understood that this product contains other homologs as indicated.

Substantially as desirable as the upper distillable polyethylene glycols, are the lower non-distillable polyethylene glycols. These materials are available in the form of a waxy water-soluble material, and the general range may vary somewhat from decato tetradeca-ethylene glycol. As

is well understood, the method of producing such glycols would cause some higher homologs to be formed; and thus, even in this instance there may be present some oxyethylene glycols within the higher range above indicated. One need not point out that these particular compounds consist of mixtures. and that in some instances, particularly desirable esters are obtained by making mixtures of the liquid nonaethylene glycol with the soft, waxy, lower non-distlllable polyethylene glycols. For the sake of convenience reference in the examples will be to nonaethylene glycol; and calculations will be based on a theoretical molecular Weight .of 414. Actually, in manufacture, the molecular weight of the glycol employed, whether a higher distillable polyethylene glycol or a lower non-distillable polyethylene glycol, or a mixture of the same, should be determined and reaction conducted on the basis of such determination, particularly in conjunction with the hydroxyl or acetyl value.

It has been previously pointed out that it is immaterial how the compounds herein contemplated are manufactured, although we have found it most desirable to react the selected glycol or mixtures of glycols with maleic anhydride in a ratio of two moles of the anhydrlde for one mole of the glycol. Under such circumstances. we have found little tendency to form longer chain polymers; and in fact, the product of reaction, if conducted at reasonably low temperatures, appears to be largely monomeric. For convenience, such intermediate product may then be considered as a dibasic or polybasic acid. One mole of the intermediate so obtained is then reacted with two moles of the alcoholic material of the kind subsequently described.

It is to be noted, however, that if one prepares a fractional acidic ester, then if two moles of the fractional acidic ester are reacted with one mole of the polyethylene glycol, there is no possibility of the formation of polymeric types of esterification products under ordinary conditions. Y

The alcoholic product employed as reactants in the manufacture of the present compounds are water-insoluble esters of trlhydric alcohols, characterized by being derived from high molal hydroxy acids and also by the fact that there is no residual hydroxyl radical attached to the polylrydric alcohol residue; 1. e., the compounds are neutral or complete esters, as differentiated from fractional esters. The polyhydric alcohols employed as reactants for the production of the neutral esters of the high molal hydroxy acids are characterized by the fact that they contain three hydroxyl groups, the commonest example being glycerol. Trihydric alcohols may be obtained by etherization reactions involving monohydric alcohols and polyhydric alcohols having more than three hydroxyl .radicals, as, for example, diglyceryl, pentaerythritol, mannitan, sorbitan, etc. The ethyl ether, butyl ether, or other alkoxy derivatives of diglycerol, is an additional illustration of this particular type. Any trlhydric alcohol. i. e., any triol, can of course be treated with an alpha-beta alkylene oxide, such as ethylene oxide, propylene oxide, or the like, so as to add an alkoxy group and still retain a terminal hydroxyl group. The oxyalkylation of glycerol by means of ethylene oxide illustrates this type. It isnot intended to include ether alcohols, particularly ether glycerols, in which the ether linkage occurs more than four times.

The trihydric alcohols or triols just described are esterified with or converted by any suitable means, into water-insoluble esters of high molal hydroxy acids having at least 8 carbon atoms and not in excess of 36 carbon atoms. The commonest example of a high molal hydroxy acid is ricinoleic acid.

Other hydroxy fatty acids include hydroxystearic acid, dihydroxystearic acid, diricinoleicacid, aleuritio acid, and the like. Similar acids are obtained in the oxidation of paraffin, petroleum hydrocarbons, or wax, and are commonly referred to as hydroxylated wax acids. Hydroxylated wax acids occur as by-products in the oxidation of waxes or similar materials, and are usually separated so that the commonest commercial form of oxidized wax acids represent mix-- tures comparatively free from the hydroxylated compounds. Hydroxylated acids are produced by other procedures, such as chlorination, either by addition or substitution, as, for example. chlorination of oleic acid or stearic acid. Subsequent reactions involve the removal of the chlorine with the introduction of a hydroxyl radical. Undecylenic acid, derived from castor oil, has been converted into a hydroxy undecanoic acid. Unsaturated hydroxy acids, such as ricinoleic acid, may be treated in various manners, so as to produce derivatives, for example, chlorinated or brominated ricinoleic acid. Such materials are. entirely satisfactory for use as reactants in the preparation of materials of the kind herein contemplated. Naturally-occurring naphthenic acids can also be converted into hydroxylated products by following similar procedure. An unsaturated hydroxy acid, such as ricinoleic acid, can be converted into a hydroxylated arylstearic acid. Such procedure contemplates reaction such as those in volving ricinoleic acid, benzene, and aluminum chloride in large excess, or involves the desulfonation of a sulfoaromatic fatty acid. In any event, by employing derivatives of undecylenic acid, or one or more of the variou wax acids, naturallyoccurring napht'henic acid, ricinoleic acid, diricinoleic acid, or derivatives thereof, as have been enumerated, one can obtain a variety of hydroxylated monocarboxy acids, having at least 11 carbon atoms and not in excess of 36 carbon atoms. Such compounds are the kind herein contemplated as reactants to furnish the alcoholiform hydroxyl.

Hydroxy acids of the kind herein contemplated may also be prepared by the hydrolysis of alphahalogen acids. For instance, alpha-bromocaproic acid, alpha-bromocapryclic acid, alphabromocapric acid, alpha-bromolauric acid, alphabrornomyristic acid, alpha-bromopalmitic acid, and the like, can be hydrolyzed to give the corresponding alpha-hydroxy acid. Indeed, a reactive alpha-halogen acid may serve as a functional equivalent of an alpha-hydroxy acid by liberation of hydrochloric acid, instead of water. Such type of reaction, however, involves numerous difliculties; and thus, it is better to employ a hydroxy acid.

In some instances derivatives of a hydroxylated unsaturated acid are most readily obtained by the employment of an intermediate in which the hydroxyl group is protected. Thus, ricinoleic acid may be acetylated, and such acetyl ricinoleic acid converted into a derivative, for instance, a derivative in which an aryl group is introduced. Such derivative can then be saponified or hydrolyzed so as to regenerate the hydroxyl radical.

As to the manufacture of various esters from acids of the kind above described, attention is directed to the following United States patents: Nos. 1,160,595, dated Nov. 16, 1915, to Gruter et al.; 2,221,674, dated Nov. 12, 1940, to Ellis; and 2,177,407, dated Oct. 24, 1939, to Hansley. See also Organic Syntheses, volume X, page 88, 1930.

AcIDIc INTERMEDIATE PRoDUcT.E:cample 1 One pound mole of nonaethylene glycol is reacted with two pound moies of maleic anhydride, so as to form nonaethylene glycol dihydrogen dimaleate.

AcIDIc INTERMEDIATE PRoDUcT.-Example 2 A mixture of lower non-distiilabie polyethylene glycols; representing approximately decato tetradeca-ethylene giycols, is substituted for nonaethylene glycol in the preceding example.

AcIDIc INTERMEDIATE PRODUCT.-E.l.ample 3 The same procedure is followed as in Intermediate product, Examples 1 and 2, except that the molar ratio 01' maleic anhydride to glycol is changed so that three pound moles of maleic anhydride are reacted with two pound moles of the glycol, so as to yield a dibasic product-which may be conveniently described as a further elaboration of the monomeric derivative described in preceding Examples 1 and 2. Such polymers form very slowly, and require higher temperature and comparatively longer period of reaction time. Also, it is desirable to add a small fraction of a suitable catalyst, say, one fourth of 1% of toluene sulfonic acid, and to pass a dried inert gas through the reaction mass.

ACIDIC INTERMEDIATE PRODUCT-Example 4 Adipic acid is substituted for maleic anhydride in Examples 1-3, preceding.

AcIDIc INTERMEDIATE PRoDUcT.Example 5 Oxalic acid is substituted for maleic anhydride in Examples 1-3, preceding.

AcIDIc INTERMEDIATE PRonUcT.Example 6 Citric acid is substituted for maleic anhydride in Examples 1-3, preceding.

ACIDIC INTERMEDIATE PRODUCT.E$G7IZPZ8 7 Succinic anhydride is substituted for maleic anhydride in Examples 1-3, preceding.

COMPOSITION or MATTER Example 1 Two pound moles of the intermediate product of the kind described in Intermediate product, Examples 1, 2 and 3 above, are reacted with two pound moles of triricinolein until substantially all dibasi'c carboxyi acidity has disappeared. The time or reaction may vary from a few hours to as much as 20 hours.

' COMPOSITION or MATTER Example 2 Beta-methyl glycerol is esterifled with ricinoleic acid to give the neutral ester, and the product so obtained is substituted for triricinolein in Composition of matter, Example 1, preceding.

ComPosITIoN or MATTER Example 3 Chlorinated triricinolein is substituted for triricinoiein in Composition of matter, Example 1, preceding.

CoMPosITIoN or MATTER Example 4 The glyceryl ester of dihydroxystearlc acid (tridihydroxystearin) is substituted for tricinolein in Composition of matter, Example 1, preceding.

COMPOSITION or MATTER Example 5 Mannitan monoethyl ether is esterified with ricinoleic acid to give the corresponding ester containing three ricinoleic radicals. This product is substituted for triricinolein in Composition of matter, Example 1, preceding.

Comrosrrron or MATTER Example 6 Mannitan monobutyl ether is substituted for mannitan monoethyl ether in Composition of matter, Example 5, preceding.

COMPOSITION or MATTER Example 7 Sorbltan monoethyl ether is substituted for mannitan monoethyl ether in Composition of matter, Example 5, preceding.

COMPOSITION or MATTER Example 8 COMPOSITION or MATTER Example .9

In Composition of matter, Examples 1-8, pre-- ceding, any residual acidity present is removed by cautiously adding a dilute solution of ammonium hydroxide until the resultant product gives a clear limpid solution in water, particularly in dilute form.

COMPOSITION or MATTER Example 10 courosmou or Mama Example 11 In Composition of matter, Examples 1-8, preceding, any residual acidity present is removed by cautiously adding a dilute solution of tris(hydroxymethyllaminomethane until the resultant product gives a clear, limpid solution in water, particularly in dilute form.

Comrosrrron or MATTER Example 12 Comosrrron or Msr'rsa Example 13 The same procedure is followed as in Composition or matter, Examples 1-11, inclusive, except that an intermediate product of the kind exemplified by Intermediate product, Example 5,

is substituted for that in Intermediate product, Examples 1, 2 and 3.

Courosrrron or MATTER Example 14 The same procedure is followed as in Composition 01 matter, Examples 1-11, inclusive, except that an intermediate product of the kind exemplified by Intermediate product, Example 6, is substituted for that in Intermediate product, Examples 1, 2 and 3.

Comrosrrrofl or MATTER Example 15 The same procedure is followed as in Composition of matter, Examplesi-ll, inclusive, ex-

cept that an intermediate product of the kind exemplified by Intermediate product, Example 7, is substituted for that in Intermediate product, Examples 1, 2 and. 3.

It is to be noted that this second step is an e'sterification reaction, and the same procedure is employed as suggested above in the preparation oi the intermediate product. Needless to say, any particular method may be used to produce the desired compounds of the kind indicated. In some instances it may be desirable to conduct the esterification reaction in the presence of a non-volatile inert solvent which simply acts as a diluent or viscosity reducer.

In the preceding examples, attention has been directed primarily'to the monomeric form, or at least, to the form in which the bifunctional alcohol, i. e., a glycol, and the polyfunctional acid, usually a bifunctional compound, react to give a chain type compound in which the adjacent acid and glycol nucleus occur as a structural unit. For instance, in the monomeric form this may be indicated in the following manner:

acid glycol acid If, however, one prepared an intermediate product employing the ratio of three moles of maleic anhydride and two males of nonaethylene glycol, the tendency would be to produce a product which might be indicated in the following manner:

neid glycol acid glycol acid .Qimilnrlv. three moles of the glycol and four moles of the acid would give a combination which may be indicated thus:

id... 1 l... id... 1 1...-

g yco ac a io i glycol acid Another way of stating the matter is that the composition may be indicated in the iollowing manner:

in which the characters have their previous significance and a: is a relatively small whole number less than 10, and probably less than 5; and in the monomeric form 2:, 01 course, is 1. The limitations on the size of a: are probably influenced largely by the fact that reaction leading to further growth is dependent upon random contact. Some of the products are self-emulsifiable oils or self-emulsifiable compounds, whereas, others give cloudy solutions 0! soi s; and the most desirable type is characterized by giving a clear solution in water, and usually in the presenceof soluble calcium or magnesium salts, and frequently in the presence of significant amounts 0! either acids or alkalies.

Water solubility can be enhanced in a number of ways which have been suggested by previous manufacturing direction, for instance:

(a) By using a more highly'polymerized ethylene glycol;

(b) By using a polymeric form instead of a monomeric form in regard to the unit which forms the chain between the (c) By using a. polybasic carboxy acid of lower molecular weight, forinstance, maleic acid, instead of adipic acid;

(d) By using an alcoholic material of lower molecular weight, for instance, ricinoleic acid glyceride, instead of the glyceride of a hy droxylated wax acid of a higher molecular weight.

In any event, it is to be noted that the compounds of the type herein contemplated are limited to the water-soluble type, i. e., those which are self-emulsifying in water, or produce a sol or a molecular solution.

Actually, a reaction involving an alcohol and an acid (esterification) may permit small amounts of either one or both of the reactants, depending upon the predetermined proportion, to remain in an unreacted state. In the actual preparation of compositions of the kind herein contemplated, any residual acidity can be removed by any suitable base, for instance, ammonia, triethanolamine, or the like, especially in dilute solution. Naturally, precaution should be taken so that neutralization takes place without saponification or decomposition of the ester. In some cases there is no objection to the presence of the acidic group. Indeed, if a tribasic acid is employed in such a manner as to leave one free carboxyl group, then it is usually desirable to neutralize such group by means of a suitable basic material.

In the hereto appended claims, reference to a neutral product refers to one in which free carboxylic radicals are absent.

Materials or the kind herein contemplated may find uses as wetting, detergent, and leveling agents in the laundry, textile. and dyeing industry; as wetting agents and detergents in the acid washing of fruit, in the acid washing of building stone and brick; as a wetting agent and preader in. the application of asphalt in road building and the like, as a constituent of soldering flux preparations; as a flotation reagent in the flotation separation of various minerals; for fiuocculation and two alcoholic nuclei;.

coagulation of various aqueous suspensions containing negatively charged particles, such as sewage, coal washing waste water, and various trade wastes and the like; as germicides, insecticides, emulsifiers for cosmetics, spray oils, water-repellent textile finish, etc. These uses are by no means exhaustive.

However, the most important phase of the present invention, as far as industrial application goes, is concerned with the use of the materials previously described as demulsifiers for water-inoil emulsions, and more specifically, emulsions of water or brine in crude petroleum.

We have found that the particular chemical compounds or reagents herein described and de-, sirable for use as demulsifiers, may also be used for other purposes, for instance, as a break inducer in doctor treatment of the kind intended to sweeten gasoline. See U. S. Patent No. 2,157,- 223, dated May 9, 1939, to Sutton.

Chemical compounds of the kind herein described are also of value as surface tension'depressants in the acidization of calcareous oilbearing strata by means of strong mineral acid, such as hydrochloric acid. Similarly, some members are effective as surface tension depressants or wetting agents in the flooding of exhausted oil-bearing strata.

As to using compounds of the kind herein described as flooding agents for recovering oil from subterranean strata, reference is made to the procedure described in detail in U. S. Patent No. 2,226,119, dated December 24, 1940, to De Groote and Keiser. As to using compounds of the kind herein described as demulsifiers, or in particular as surface tension depressants in combination with mineral acid or acidization of oil-bearing strata, reference is made to U. S. Patent No. 2,233,383, dated February 25, 1941, to De Groote and Kaiser.

It will be apparent to those skilled in the art that residual carboxyl acidity can be eliminated by esterification with a low molal alcohol, for instance, ethyl, methyl, or propyl alcohol, by conventional procedure, so as to give a substantially neutral product. The introduction of such low molal hydrophobe groups does not seriously affect the solubility, and in some instances, gives increased resistance, to soluble calcium and magnesium salts, for such property is of particular value. Usually, however, neutralization with a dilute solution of ammonia or the like is just as practicable and less expensive.

Having thus described our invention, what we claim as new and desire to secure by Letters Patent is;

1. A water-soluble ester, being the resultant of two intermediate reactants, to wit, an acidic intermediate reactant and an alcoholic intermediate reactant; said acidic intermediate reactant being in turn the resultant fractional ester of two primary reactants one being alcoholic and the other acidic; said primary alcoholic reactant consisting of a polyalkylene glycol having at least 7 and not more than 1'7 ether linkages; and the alkylene radical thereof containing at least two and not more than 6 carbon atoms; and the acidic primary reactant being a polybasic carboxy acid having not more than 6 carbon atoms; and the,

ratio of the said primary esterifying reactants being within the range of more than 1 mole and not over 2 moles of the polybasic acid for each mole of the polyalkylene glycol; and the said intermediate alcoholic reactant being the complete ester of 2 additional primary reactants, and likewise, one being acidic and the other alcoholic, to wit, a high molal monocarboxy hydroxy acid having at least 8 and not more than 32 carbon atoms; and a triol; the ratio 'of the intermediate reactants being 2 moles of the alcoholic intermediate reactant for each mole of the acidic intermediate reactant.

2. A water-soluble ester, as defined in claim 1, with the added proviso that said ester must be neutral.

3. A water-soluble ester, as defined in claim 1, with the added proviso that said ester must be neutral and that the polybasic .primary reactant be a dibasic carboxy acid having not more than 6 carbon atoms.

4. A water-soluble ester, as defined in claim 1, with the added proviso that said ester must be neutral; that the polybasic primary reactant be a dibasic carboxy acid having not more than 6 carbon atoms; and that the primary dihydric alcoholic reactant be a polyethylene glycol having at least 7 and not more than 17 ether linkages.

5. A water-soluble ester, as defined in claim 1, with the added proviso that said ester must be neutral; that the polybasic primary reactant be a dibasic carboxy acid having not more than 6 carbon atoms; that the primary dihydric alcoholic reactant be a polyethylene glycol having at least 7 and not more than 1'1 ether linkages; and the acyl radical of the high molal monocarboxy hydroxy acid containing 18 carbon atoms.

6. A neutral water-soluble chemical compound, as defined in claim 1, and of the following structural formula:

TOOC.D.COO(CzH4O)-mCzH4OOC.D.COO.T

in which T is a triol triricinoleate radical; and D is the dibasic acid residue; and m represents a numeral varying from '7 to 12.

8. A neutral water-soluble chemical compound, as defined in claim 1, and of the following structural formula:

TOOC.D.COO CzHsO) mC2H46OC.D.COO.T

in which T is a triol triricinoleate radical; and D is a maleic acid residue; and m represents a numeral varying from 7 to 12.

9. A neutral water-soluble chemical compound, as defined in claim 1, and of the following structural formula:

TOOC.D.COO Cal-I40) mC2H4OOC.D.COO.T

in which T is a trial triricinoleate radical; and D is a succinic acid residue; and m represents a numeral varying from 7 to 12. I

10. A neutral water-soluble chemical com- .pound, as defined in claim 1, and of the following structural formula:

in which T is a. triol triricinoleate radical; and D is an. adipic acid residue; and m represents numeral varying from 7 to 12.

11. In the method of manufacturing a-watersoluble ester, being the resultant of two intermediate reactants, to wit, an acidic intermediate reactant and an alcoholic intermediate reactant; said acidic intermediate reactant being in turn the resultant fractional ester of two primary reactants, one being alcoholic and the other acidic; said primary alcoholic reactant consisting of a polyalkylene glycol having at least 7 and not more than 17 ether linkages; and the alkylene radical thereof containing at least two and not more than 6 carbon atoms; and the acidic primary reactant being a polybasic carboxy acid having not more than 6 carbon atoms; and the ratio of the said primary esterifying reactants being within the range of more than 1 mole and not over 2 moles of the polybasic acid for each mole of the polyalkylene glycol; and the said intermediate alcoholic reactant being the complete ester of 2 additional primary reactants, and like-- wise, one being acidic and the other alcoholic, to wit, a high molal monocarboxy hydroxy acid having at least 8 and not more than 32 carbon atoms; and a triol, the ratio of the intermediate reactants being 2 moles of the alcoholic intermediate reactant for each mole of the acidic intermediate reactant; the steps of: (A) esteriiying the triol with the high molal monocarboxy hydroxy acid to yield the alcoholic intermediate reactant; (B) reacting the polyalkylene glycol with the polybasic carboxy acid to yield the acidic intermediate reactant; and (C) subsequently reacting said intermediate reactants to yield a water-soluble ester.

MELVIN DE GROOTE.

BERNHARD KEISER.

, CERTIFICATE OF -CORBECTION. Patent No. 2,550, 72. September 28, 1911.5.

MELVIN DE GROOTE ET AL.

It 15 hereby certified that "error appears in the above numbered'paten requiring'correction as follows: In the heading to the printed specifica tion, line 11, for the serial number "h8h,686" read -hlL8,686-; and the said Letters Patent should be read with this correction therein 191M: the same may conform to the record of the case in the Patent Office.

Signed and sealed this 16th day of November, A. D. 19%.

Henry Van Arsdale, (Seal) Acting Commissioner of Patents. 

